University of Oulu

Miettinen, J., Koskenniska, S., Somani, M. et al. Optimization of CCT Equations Using Calculated Grain Boundary Soluble Compositions for the Simulation of Austenite Decomposition of Steels. Metall and Materi Trans B 50, 2853–2866 (2019).

Optimization of CCT equations using calculated grain boundary soluble compositions for the simulation of austenite decomposition of steels

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Author: Miettinen, Jyrki1; Koskenniska, Sami2; Somani, Mahesh2;
Organizations: 1Process Metallurgy Research Group, University of Oulu, P.O. Box 8000, 90014, Oulu, Finland
2Material and Mechanical Engineering, University of Oulu, P.O. Box 8000, 90014, Oulu, Finland
3Department of Materials Science and Engineering, Aalto University, Vuorimiehentie 2, 02150, Espoo, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.7 MB)
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Language: English
Published: Springer Nature, 2019
Publish Date: 2020-03-04


New CCT equations have been developed and optimized to simulate the start temperatures of the austenite decomposition process in low-alloyed steels using experimental CCT data published in the literature. Exceptionally, this optimization does not apply the nominal compositions of the steels, but the corresponding soluble compositions of the grain boundaries calculated using IDS software, depending on the reported austenitization treatments of the steels. These compositions, rather than the nominal ones, are expected to control the start of the austenite decomposition, which usually initiates at the grain boundaries. The new optimization treatment takes into account the solute microsegregation and the possible precipitate formation. Using IDS software, the new equations were validated with new experimental CCT data. Agreement was good not only for the austenite decomposition start temperatures, but also for the final phase fractions, indicating fairly reasonable predictions of phase transformation kinetics by the IDS. In addition, IDS simulations were compared with the experimental CCT data of five high-carbon steels, applying both the new equations based on grain boundary soluble compositions as well as the equations based on the nominal compositions. With the same experimental CCT data used in optimization, better agreement was obtained with the new equations, indicating the importance of determining the soluble compositions at the grain boundaries where the austenite decomposition process is likely to begin.

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Series: Metallurgical and materials transactions. B, Process metallurgy and materials processing science
ISSN: 1073-5615
ISSN-E: 1543-1916
ISSN-L: 1073-5615
Volume: 50
Issue: 6
Pages: 2853 - 2866
DOI: 10.1007/s11663-019-01698-7
Type of Publication: A1 Journal article – refereed
Field of Science: 215 Chemical engineering
216 Materials engineering
Funding: Open access funding provided by University of Oulu including Oulu University Hospital. The funding of this research activity under the auspices of the Genome of Steel (Profi3) project by the Academy of Finland through Project #311934 is gratefully acknowledged.
Copyright information: © The Author(s) 2019. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.